Designing the physical metallurgy of a bainitic microalloyed steel with a dilatometer

During the past decade, medium carbon microalloyed steels have become increasingly important in the automotive sector. These steels are especially suitable for automobile components such as connecting rods, crankshafts and wheel hubs. Their mechanical properties are generally adequate in most cases although their toughnesses are consistently low. High toughness can be obtained in medium carbon microalloyed bainitic steel (38MnV7) after a careful control of the chemistry and heat thermal treatment. An specific chemical composition of a 38MnV7 steel has been developed, providing impact energies after Charpy-V tests at room temperature as high as 40J (the steel in bainitic state). Present work is oriented to an optimization of the above chemical composition by control of the Transformation Time Temperature (TTT) curves as well as the Precipitation Time Temperatures (PTT) curves of the present microallying elements. To attain this purpose six different casting were prepared, ranging the chemical composition as follows %C: 0.35-0.46, %Mn: 1.33-1.84, %V: 0.066-0.14% and %Ti: 0.010- 0.025. To appropriate design the thermal cycle, TTT curves were determined for each steel at two austenitization conditions, in order to promote fine and large initial grain sizes.. PTT curves were determined by the stress relaxation technique, a method which can be also be used to derive recrystrallization kinetics. All curves, TTT and PTT curves where derived by using a quenching dilatometer Bahr DIL805A/D. While the TTT curves were obtained in a classical way, the relaxation test consist in sample austenization followed by cooling down to the testing temperature. After a short stabilization period of 10s, samples are deformed to different strain levels and then relaxed, i.e. deformation is kept constant and the variation of the stress with the time is recorded. The different deformation levels are selected to evaluate the effect of deformation on precipitation characteristics. The relaxation curves under these conditions gave information about the kinetics of precipitation when there is no plastic deformation and, thus, generation of dislocations involved. Results are finally discussed in terms of the chemical composition, initial microstructure and precipitates interaction.Peer Reviewe

Toxicity of several d-endotoxins of Bacillus thuringiensis against Helicoverpa armigera (Lepidoptera: Noctuidae) from Spain

Toxicity and larval growth inhibition of eleven insecticidal proteins of Bacillus thuringiensis were evaluated against neonate larvae of Helicoverpa armigera, a major pest of important crops in Spain and other countries, by a whole-diet contamination method. The most active toxins were Cry1Ac4 and Cry2Aa1, with LC50 values of 3.5 and 6.3 μg/ml, respectively. At the concentrations tested, Cry1Ac4, Cry2Aa1, Cry9Ca, Cry1Fa1, Cry1Ab3, Cry2Ab2, Cry1Da, and Cry1Ja1, produced a significant growth inhibition, whereas Cry1Aa3, Cry1Ca2, and Cry1Ea had no effect

Temporal stimulated intersubband emission of photoexcited electrons

We have studied the transient evolution of electrons distributed over two levels in a wide quantum well, with the two levels below the optical phonon energy, after an ultrafast interband excitation and cascade emission of optical phonons. If electrons are distributed near the top of the passive region, a temporal negative absorption appears to be dominant in the intersubband response. This is due to the effective broadening of the upper level state under the optical phonon emission. We have then considered the amplification of the ground mode in a THz waveguide with a multiquantum well placed at the center of the cavity. A huge increase of the probe signal is obtained, which permits the temporal stimulated emission regime of the photoexcited electrons in the THz spectral region.Comment: 5 pages, 5 figures, brief repor

Effects of Jatropha lubricant thermo-oxidation on the tribological behaviour of engine cylinder liners as measured by a reciprocating friction test

Bio-lubricants have emerged as a potential and viable way to replace, totally or partially, mineral oils due to their effectiveness in the boundary lubrication regime for different applications, including, automotive engine operation. However, the effect of thermo-oxidation caused by the long-term use of the bio-lubricants on their tribological properties has been scarcely analysed. In this work, the effect of thermo-oxidation of Jatropha oil (JO), an engine mineral oil (EMO) and a blend made up of 80%vol. EMO and 20%vol. JO (B20) on the tribological behaviour of a simulated piston ring/engine cylinder liner interface was studied in reciprocating friction tests at 26 and 100 °C. The oils were thermally oxidized and characterized in terms of carbonyl compounds, depletion of ZDDP additives, changes in kinematic viscosity and viscosity index. Friction coefficients, wear rates and scar morphologies were assessed. Thermo-oxidation resulted in significant viscosity increases in JO compared to EMO and B20. Also, it generated increased friction coefficients for JO and B20. However, they were lower than those for fresh and aged EMO. EMO increased the wear rate after thermo-oxidation in contrast to JO. Smearing was generated using most oil samples while severe scuffing was only produced by using fresh JO at 100 °C

On the implementation of a dynamic direction modulation system with vector modulators

Dynamic directional modulation (DDM) has already proven to be an efficient technique to achieve physical layer security in wireless communications. System architectures based on vector modulators provide a flexible framework to implement synthesis methods that allow us to obtain increased security and/or independent multichannel transmissions. However, the implementation of DDM with vector modulators requires an accurate calibration (amplitude and phase) of every component in the RF path. In this contribution, we study the sensitivity of the response of a DDM system based on commercial vector modulators showing how to correct the nonideal behavior of all the components thanks to the flexibility provided by the vector modulator

Experimental measurement of the quality factor of a Fabry-P\'erot open-cavity axion haloscope

The axion is a hypothetical boson arising from the most natural solution to the problem of charge and parity symmetry in the strong nuclear force. Moreover, this pseudoscalar emerges as a dark matter candidate in a parameter space extending several decades in mass. The Dark-photons \& Axion-Like particles Interferometer (DALI) is a proposal to search for axion dark matter in a range that remains under-examined. Currently in a design and prototyping phase, this haloscope is a multilayer Fabry-P\'erot interferometer. A proof-of-principle experiment is performed to observe the resonance in a prototype. The test unveils a quality factor per open cavity of a few hundred over a bandwidth of the order of dozens of megahertz. The result elucidates a physics potential to find the, so far elusive, axion, in a sector which can simultaneously solve the symmetry problem in the strong interaction and the enigma of dark matter.Comment: 5 pages, 6 figure

Cultura y clima de la seguridad como factores de protección frente a los riesgos ocupacionales

La presente revisión bibliográfica es una contextualización acerca del Clima y la Cultura de Seguridad Organizacional, así como también algunos de los instrumentos y formas de medición más utilizados para evaluar estas temáticas. Se pretendió afirmar o probar que tanto la Cultura como el Clima de Seguridad en las distintas organizaciones, pueden convertirse en factores de protección ante los riesgos ocupacionales; e incluso como factores predictores ante la ocurrencia de la accidentalidad y siniestralidad laboral. Para llevar a cabo esta monografía fue necesario revisar muchos artículos, teniendo preferencia aquellos estudios que fueron realizados y publicados en los últimos quince años. Como resultado, se puede decir que las investigaciones realizadas al respecto muestran algunas limitaciones, nuevas direcciones a tomar, además apuntan a confirmar que tan protectores pueden llegar a ser la cultura y el clima de seguridad frente a la percepción que tengan los empleados sobre los riesgos a los que están expuestos a diario en sus sitios de trabajo.Incluye bibliografí

Modelado 3D de la muralla de la Macarena (Sevilla). Propuesta metodológica para su integración en trabajos de gestión cartográfica digital

[EN] Conservation studies of an architectural asset constitute a solid support for future interventions. In particular, Digital Cartographic Management advocates the use of simplified models that allow different levels of definition to be achieved, depending on the desired architectural scale. Based on previous studies in which four levels of definition have been achieved, the aim is to define a fifth level from a 3D model. For this purpose, the Macarena Wall (Seville) is proposed as a case study. In this work, a photogrammetric survey of a section of the sector of this medieval wall is carried out, from which the entities that will form part of a fifth level of definition are identified.[ES] Los estudios de conservación sobre un bien arquitectónico constituyen un soporte sólido para futuras intervenciones. En concreto, la Gestión Cartográfica Digital aboga por el uso de modelos simplificados que permiten alcanzar distintos niveles de definición, según la escala arquitectónica deseada. Partiendo de estudios previos en los que se han logrado obtener cuatro niveles de definición, se tiene como objetivo definir un quinto nivel a partir de un modelo 3D. Para ello, se propone como caso de estudio la Muralla de La Macarena (Sevilla). En este trabajo se realiza el levantamiento fotogramétrico de un tramo del sector de esta muralla medieval, a partir del cual se identifican las entidades que formarán parte de un quinto nivel de definición.Los autores expresan su agradecimiento a la Gerencia de Urbanismo del Ayuntamiento de Sevilla, especialmente al Servicio de Conservación Urbana y Renovación de la Edificación, al Servicio de Planeamiento y Desarrollo Urbanístico y a la Infraestructura de Datos Espaciales de Sevilla (IDE Sevilla).Cabrera-Revuelta, E.; Mascort-Albea, EJ.; Hidalgo-Sánchez, FM.; Romero-Hernández, R.; Canivell, J. (2021). 3D modeling of the Macarena Wall (Seville). Methodological proposal for its integration in digital cartographic management studies. EGE Revista de Expresión Gráfica en la Edificación. 0(14):4-23. https://doi.org/10.4995/ege.2021.15584OJS423014Alshawabkeh, Y., El-Khalili, M., Almasri, E., Bala'awi, F., & Al-Massarweh, A. 2020. Heritage documentation using laser scanner and photogrammetry. The case study of Qasr Al-Abidit, Jordan. Digital Applications in Archaeology and Cultural Heritage, vol. 16, e00133. https://doi.org/10.1016/j.daach.2019.e00133Angulo, R., Pinto, F., Rodríguez, J., & Palomino, A. 2017. Digital Anastylosis of the Remains of a Portal by Master Builder Hernán Ruiz: Knowledge Strategies, Methods and Modelling Results. Digital Applications in Archaeology and Cultural Heritage, vol. 7 (March), pp. 32-41. https://doi.org/10.1016/j.daach.2017.09.003Barrera, J.A., Macías, D.H., & Boquera, J.H. 2005. La muralla almohade de Sevilla: aplicación de tecnologías de vanguardia a los levantamientos en arqueología y restauración. Aparejadores: Boletín Del Colegio Oficial de Aparejadores y Arquitectos Técnicos de Sevilla, no. 69, p. 48.Barrera Vera, J.A. 2005. Generation of virtual models of historical tapial 1 walls in Seville (Spain).Benavides López, J.A., & Barrera Vera, J A. 2020. Evaluación de los Sistemas de Mapeo Móvil (MMS) en la documentación gráfica del tholo de El Romeral (Conjunto Arqueológico Dólmenes de Antequera). Arqueología de la Arquitectura, vol. 17, e095. https://doi.org/10.3989/arq.arqt.2020.004Cabeza Méndez, J.M. 1993. Restauración de las murallas de Sevilla. Arquitectura y Ciudad II y III: Seminarios celebrados en Melilla, los días 25, 26 y 27 de septiembre de 1990 y los días 24, 25 y 26 de septiembre de 1991, pp. 341-348.Cabrera-Revuelta, E., & Molero-Alonso, B. 2016. Fotogrametría terrestre. Trabajos previos a la toma de datos. EGE Revista de Expresión Gráfica en la Edificación, no. 9, pp. 33-44. https://doi.org/10.4995/ege.2016.12458Cabrera-Revuelta, E., Chávez, M.J., Barrera-Vera, J.A., Fernández-Rodríguez, Y., & Caballero Sánchez, M. 2021. Optimization of laser scanner positioning networks for architectural surveys through the design of genetic algorithms. Measurement, vol. 174, 108898. https://doi.org/10.1016/j.measurement.2020.108898Calama, J.M., & Canivell, J. 2006. Análisis patológico de los paramentos de la muralla almohade de Sevilla (tramo comprendido entre la Puerta de la Macarena y el Jardín del Valle). V SIACOT. I SAACT. Construir con Tierra. Ayer y Hoy. Libro de Resúmenes. 14-17 june 2006, Mendoza, Argentina, pp. 117-118.Canivell, Jacinto et al. 2020. "A Methodological Framework for the Preventive Conservation of Historic Walls Located in Urban Contexts. Spatial Data Standards for the Medieval Wall of Seville (Spain): The Case of the Macarena Sector." Ge-Conservacion 18(1): 44-55. https://doi.org/10.37558/gec.v18i1.762Canivell, J., Jaramillo-Morilla, A., Mascort-Albea, E.J., & Romero-Hernández, R. 2019. Metodología de evaluación y monitorización del patrimonio basado en la gestión cartográfica digital. La muralla de Sevilla. In M.D. Sivo, D. Ladiana (Ed.), Le Mura Urbane Crollano: Conservazione e Manutenzione Programmata Della Cinta Muraria Dei Centri Storici: Atti del Seminario Internazionale.(pp. 119-135). Pisa: Pisa University Press. https://hdl.handle.net/11441/88061Canivell, J., Mascort-Albea, E.J., Cabrera-Revuelta, E., Romero-Hernández, R., Jaramillo-Morilla, A., & Serrano-Chacón, Á. 2020. A methodological framework for the preventive conservation of historic walls located in urban contexts. Spatial data standards for the medieval wall of Seville (Spain): the case of the Macarena sector. Ge-Conservacion, vol. 18, no. 1, pp. 44-55. https://doi.org/10.37558/gec.v18i1.762Chiabrando, F., Colucci, E., Lingua, A., Matrone, F., Noardo, F., & Spanòa, A. 2018. A European Interoperable Database (EID) to increase resilience of cultural heritage. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. 42, no. 3/W4, pp. 151-158. https://doi.org/10.5194/isprs-archives-XLII-3-W4-151-2018Henriques, F., Bailão, A., Rocha, J., & Costa, J. 2020. Restoration of an 18th century frame: 3D modelling, printing and matching color of decorative flowers elements. Ge-Conservacion, vol. 18, no. 1, pp. 313-322. https://doi.org/10.37558/gec.v18i1.854Hidalgo-Sánchez, F.M. 2018. Interoperatividad entre SIG y BIM aplicada al patrimonio arquitectónico, exploración de posibilidades mediante la realización de un modelo digitalizado de la Antigua Iglesia de Santa Lucía y posterior análisis. Final Degree Work. Universidad de Sevilla, Sevilla. https://hdl.handle.net/11441/79394Jiménez-Maqueda, D., & Pérez-Quesada, P. 2012. La muralla huérfana. A vueltas con el último recinto amurallado de Madnat Išblia. Romula, no. 11, pp. 273-347. López-Martínez, F.J. 1999. Tapias y tapiales. Loggia: Arquitectura y Restauración, no. 8, pp. 74-89. https://doi.org/10.4995/loggia.1999.5288Martín-del-Río, J.J., Alejandre, F.J., Blasco-López, F.J., & Márquez-Martínez, G. 2008. Hormigones de cal islámicos: altas resistencias en los tapiales del sector oriental de la Muralla de Sevilla (España). Actas de IX CICOP 2008. Congreso Internacional de Rehabilitación del Patrimonio Arquitectónico y Edificación. Patrimonio Construido e Innovación., Sevilla, vol. I, pp. 81-86.Masciotta, M.G., Morais, M.J., Ramos, L.F., Oliveira, D.V, Sánchez-Aparicio, L.J., & González-Aguilera, D. 2019. A Digital-based Integrated Methodology for the Preventive Conservation of Cultural Heritage: The Experience of HeritageCare Project. International Journal of Architectural Heritage, pp. 1-20. https://doi.org/10.1080/15583058.2019.1668985Mascort-Albea, E.J., Jaramillo-Morilla, A., Romero-Hernández, R., & Hidalgo-Sánchez, F.M. 2020. BIM-GIS interoperability applied to architectonic heritage: 2D and 3D digital models for the study of the ancient church of Santa Lucía in Seville (Spain). Science and Digital Technology for Cultural Heritage: Interdisciplinary Approach to Diagnosis, Vulberability, Risk Assessment and Graphic Information Models, CRC Press. pp. 31-35. https://doi.org/10.1201/9780429345470-5Merchán, M.J., & Pérez, E. 2020. Conservation to overcome oblivion. New methods for the survival of lost heritage memory. Ge-Conservacion, no. 17, pp. 160-170. https://doi.org/10.37558/gec.v17i1.753Piaia, E., Maietti, F., Di Giulio, R., Schippers-Trifan, O., Van Delft, A., Bruinenberg, S., & Olivadese, R. 2020. BIM-based cultural heritage asset management tool. Innovative solution to orient the preservation and valorization of historic buildings. International Journal of Architectural Heritage, pp. 1-24. https://doi.org/10.1080/15583058.2020.1734686Pierdicca, R. 2018. Mapping Chimu's settlements for conservation purposes using UAV and close range photogrammetry. The virtual reconstruction of Palacio Tschudi, Chan Chan, Peru. Digital Applications in Archaeology and Cultural Heritage, vol. 8, pp. 27-34. https://doi.org/10.1016/j.daach.2017.11.004Quattrini, R., Pierdicca, R., Paolanti, M., Clini, P., Nespeca, R., & Frontoni, E. 2020. Digital interaction with 3D archaeological artefacts: evaluating user's behaviours at different representation scales. Digital Applications in Archaeology and Cultural Heritage, vol. 18, e00148. https://doi.org/10.1016/j.daach.2020.e00148Rubio, J.M., Martín, J.J.F., & Alonso, J.I.S.J. 2018. Implementation of 3D scanner and digital photogrammetry in the documentation process of la Merced Church, Panama. EGA Revista de Expresion Grafica Arquitectonica, vol. 23, no. 32, pp. 208-219. https://doi.org/10.4995/ega.2018.9811Sequenzia, G., Fatuzzo, G., & Oliveri, S.M. 2021. A computer-based method to reproduce and analyse ancient series-produced moulded artefacts. Digital Applications in Archaeology and Cultural Heritage, vol. 20, e00174. https://doi.org/10.1016/j.daach.2021.e0017